netdev - Re: [PATCH RFC net] net: dsa: mv88e6xxx: allow use of PHYs on CPU and DSA ports

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Message-ID: <Ya91rX5acIKQk7W0@lunn.ch>
Date:   Tue, 7 Dec 2021 15:54:37 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Cc:     Martyn Welch <martyn.welch@...labora.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Subject: Re: [PATCH RFC net] net: dsa: mv88e6xxx: allow use of PHYs on CPU
 and DSA ports

On Tue, Dec 07, 2021 at 10:59:19AM +0000, Russell King (Oracle) wrote:
> Martyn Welch reports that his CPU port is unable to link where it has
> been necessary to use one of the switch ports with an internal PHY for
> the CPU port. The reason behind this is the port control register is
> left forcing the link down, preventing traffic flow.
> 
> This occurs because during initialisation, phylink expects the link to
> be down, and DSA forces the link down by synthesising a call to the
> DSA drivers phylink_mac_link_down() method, but we don't touch the
> forced-link state when we later reconfigure the port.
> 
> Resolve this by also unforcing the link state when we are operating in
> PHY mode and the PPU is set to poll the PHY to retrieve link status
> information.
> 
> Reported-by: Martyn Welch <martyn.welch@...labora.com>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

Hi Russell

It would be good to have a Fixes: tag here, to help with back porting.

The concept looks good, and i see you now have a Tested-by:, so with
the fixup applied i think you are good to go. Please add my
Reviewed-by: to the next version.

   Andrew